docs: getValue() replaced with node

[ssssota]

Description

getValue function is deprecated.

prettier/src/index.d.ts

Lines 110 to 113 in 1264a4c

	/**
	* @deprecated Please use `AstPath#node` or `AstPath#siblings`
	*/
	getValue(): T;

However, the plugin documentation still uses getValue function.

Checklist

• I’ve added tests to confirm my change works.
• (If changing the API or CLI) I’ve documented the changes I’ve made (in the docs/ directory).
• (If the change is user-facing) I’ve added my changes to changelog_unreleased/*/XXXX.md file following changelog_unreleased/TEMPLATE.md.
• I’ve read the contributing guidelines.

✨Try the playground for this PR✨